U.S. patent number 7,094,442 [Application Number 10/891,355] was granted by the patent office on 2006-08-22 for methods for the reduction and elimination of particulate contamination with cvd of amorphous carbon.
This patent grant is currently assigned to Applied Materials, Inc.. Invention is credited to Heraldo L. Botelho, Sudha S. R. Rathi, Martin Jay Seamons, Wendy H. Yeh.
United States Patent |
7,094,442 |
Seamons , et al. |
August 22, 2006 |
**Please see images for:
( Certificate of Correction ) ** |
Methods for the reduction and elimination of particulate
contamination with CVD of amorphous carbon
Abstract
A method is provided for forming an amorphous carbon layer,
deposited on a dielectric material such as oxide, nitride, silicon
carbide, carbon doped oxide, etc., or a metal layer such as
tungsten, aluminum or poly-silicon. The method includes the use of
chamber seasoning, variable thickness of seasoning film, wider
spacing, variable process gas flows, post-deposition purge with
inert gas, and post-deposition plasma purge, among others, to make
the deposition of an amorphous carbon film at low deposition
temperatures possible without any defects or particle
contamination.
Inventors: |
Seamons; Martin Jay (San Jose,
CA), Yeh; Wendy H. (Mountain View, CA), Rathi; Sudha S.
R. (San Jose, CA), Botelho; Heraldo L. (Palo Alto,
CA) |
Assignee: |
Applied Materials, Inc. (Santa
Clara, CA)
|
Family
ID: |
35600030 |
Appl.
No.: |
10/891,355 |
Filed: |
July 13, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060014397 A1 |
Jan 19, 2006 |
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Current U.S.
Class: |
427/122;
257/E21.27; 427/569; 427/255.5; 438/790; 438/789; 438/482;
427/249.1 |
Current CPC
Class: |
H01L
21/3146 (20130101); C23C 16/4401 (20130101); H01L
21/02274 (20130101); H01L 21/02115 (20130101); H01L
21/02271 (20130101); C23C 16/4405 (20130101); C23C
16/4404 (20130101); C23C 16/26 (20130101) |
Current International
Class: |
B05D
5/12 (20060101) |
Field of
Search: |
;427/255.5,122 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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103 28 578 |
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Feb 2004 |
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DE |
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0 381 109 |
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Jan 1990 |
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EP |
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0 901 156 |
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Mar 1999 |
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EP |
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09 045633 |
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Feb 1997 |
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JP |
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11 026578 |
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Jan 1999 |
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JP |
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WO 00/05763 |
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Feb 2000 |
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WO |
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Other References
A Helmbold et al., "Electrical Conductivity of Amorphous
Hydrogenated Carbon", Philosophical Magazines B., 1995, vol. 72,
No. 3, pp. 335-350. cited by other .
Liu, et al., "Generating Sub-30nm Poly-Silicon Gates Using PECVD
Amorphous Carbon as Hardmask and Anti-Reflective Coating",
Proceedings of the SPIE, Bellingham, VA, US, vol. 5040, No. 1, Feb.
25, 2003, pp. 841-848. cited by other .
PCT Notification of Transmittal of the International Search Report
dated May 31, 2005 for PCT/US05/008070. cited by other .
PCT Written Opinion dated May 31, 2005 for PCT/US05/008070. cited
by other.
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Primary Examiner: Whitehead, Jr.; Carl
Assistant Examiner: Rodgers; Colleen E.
Attorney, Agent or Firm: Patterson and Sheridan
Claims
What is claimed is:
1. A method for processing a substrate in a chamber, comprising:
positioning a substrate inside the chamber; providing a gas mixture
by flowing one or more hydrocarbon compounds and an inert gas to
the deposition chamber; applying an electric field to the gas
mixture and heating the gas mixture to decompose the one or more
hydrocarbon compounds in the gas mixture and generate a plasma;
depositing a material on the substrate for a deposition time;
moving the substrate to a different distance from a gas
distribution system of the chamber; and then terminating at least
one gas flow of the one or more hydrocarbon compounds while still
flowing the inert gas to the deposition chamber for a first time
period, wherein any gas or plasma generated is pumped out of the
chamber for a second time period, thereby reducing particle
contamination on the substrate.
2. The method of claim 1, further comprising cleaning the chamber
with a cleaning plasma before positioning the substrate, wherein
the cleaning plasma is generated by flowing a cleaning gas into the
chamber and applying an electric field.
3. The method of claim 2, wherein the cleaning gas is selected from
the group consisting of oxygen-containing gas, hydrogen-containing
gas, nitrogen-containing gas, oxygen gas, hydrogen gas, carbon
dioxide, nitrous oxide, ammonium, helium, argon, and combinations
thereof.
4. The method of claim 1, further comprising depositing the same
material inside the chamber before positioning the substrate inside
the chamber and depositing the material on the substrate.
5. The method of claim 4, wherein the same material is deposited
inside the chamber for a deposition time of between about 5 seconds
to about 30 seconds.
6. The method of claim 1, wherein the material is an amorphous
carbon.
7. The method of claim 1, wherein the substrate is heated to a
temperature between about 1000 C and about 6000 C.
8. The method of claim 1, wherein the deposition time is between
about 5 seconds or longer.
9. The method of claim 1, wherein the first time period is between
about 5 seconds to about 1 minute.
10. The method of claim 1, wherein the second time period is
between about 5 seconds to about 3 minutes.
11. The method of claim 1, wherein the one or more hydrocarbon
compounds comprises the general formula C.sub.xH.sub.y, wherein x
has a range of 1 to 8 and y has a range of 2 to 18.
12. The method of claim 1, wherein the one or more hydrocarbon
compounds are selected from the group consisting of methane
(CH.sub.4), ethane (C.sub.2H.sub.6), ethene (C.sub.2H.sub.4),
propylene (C.sub.3H.sub.6), propyne (C.sub.3H.sub.4), propane
(C.sub.3H.sub.8), butane (C.sub.4H.sub.10), butylene
(C.sub.4H.sub.8), butadiene (C.sub.4H.sub.6), acetelyne
(C.sub.2H.sub.2), benzene (C.sub.6H.sub.6), methyl benzene
(C.sub.7H.sub.8), and combinations thereof.
13. The method of claim 1, wherein the electric field is generated
by applying a power source selected from the group consisting of
radiofrequency power, microwave frequency, and combinations
thereof, and coupling to the deposition chamber in a way selected
from the group consisting of inductively coupling, and capacitively
coupling.
14. The method of claim 13, wherein the power source is turned off
while the at least one gas flow of the one or more hydrocarbon
compounds is terminated.
15. The method of claim 13, wherein the power source is still
turned on while the at least one gas flow of the one or more
hydrocarbon compounds is terminated.
16. The method of claim 1, wherein the inert gas is selected from
the group consisting of helium, argon and combinations thereof.
17. The method of claim 1, wherein the substrate is moved to a
different distance from a gas distribution system to be close to an
exhaust of the chamber.
18. The method of claim 1, wherein the substrate is moved to a
loading/unloading position.
Description
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to the fabrication of integrated circuits and
to a method for depositing a layer on a substrate and the
structures formed by the layer.
2. Description of the Related Art
In the manufacture of integrated circuits, chemical vapor
deposition processes are often used for deposition or etching of
various material layers. Conventional thermal CVD processes supply
reactive compounds to the substrate surface where heat-induced
chemical reactions take place to produce a desired layer. Plasma
enhanced chemical vapor deposition (PECVD) processes employ a power
source (e.g., radio frequency (RF) power or microwave power)
coupled to a deposition chamber to increase dissociation of the
reactive compounds. Thus, PECVD processes allow deposition to be
achieved at lower temperatures than those required for analogous
thermal processes. This is advantageous for processes with
stringent thermal budget demands, e.g., in very large scale or
ultra-large scale integrated circuit (VLSI or ULSI) device
fabrication.
The demands for greater integrated circuit densities also impose
demands on the process sequences used for integrated circuit
manufacture. For example, in process sequences using conventional
lithographic techniques, a layer of energy sensitive resist is
formed over a stack of material layers on a substrate. An image of
a pattern is introduced into the energy sensitive resist layer.
Thereafter, the pattern introduced into the energy sensitive resist
layer is transferred into one or more layers of the material stack
formed on the substrate using the layer of energy sensitive resist
as a mask and a chemical etchant. The chemical etchant is designed
to have a greater etch selectivity for the material layers of the
stack than for the energy sensitive resist. That is, the chemical
etchant etches the one or more layers of the material stack at a
much faster rate than it etches the energy sensitive resist to
prevent the energy sensitive resist material from being consumed
prior to completion of the pattern transfer.
A hardmask can be over the exposed material stack to enhance
patterning and etching of feature definitions in the material
stack. The hardmask is resistive to damage and deformation. The
hardmask protects the underlying material stack during subsequent
material deposition and planarization or material removal
processes, such as chemical mechanical polishing techniques or
etching techniques, to reduce defect formation and feature
deformation. The hardmask may then be removed following
planarization prior to subsequent processing of the substrate.
One material of interest as a hardmask is amorphous carbon.
Amorphous carbon has a low dielectric constant (i.e., k<4) and a
sufficiently high resistance to removal from etching and polishing
techniques for performing as a hardmask. The use of amorphous
carbon in semiconductor processing is favorable because it provides
good etch selectivity with oxides and metals and is also an
anti-reflective coating (ARC) material at deep ultra-violet (DUV)
wavelengths. In addition, it is easily stripped away after pattern
transfer. Further, it enables gate lengths at less than 100 nm
(e.g., less than 60 nm) and contact holes at less than 150 nm
(e.g., less than 110 nm) with aspect ratios of more than 5:1 (e.g.,
more than 8:1).
When depositing an amorphous carbon film on a substrate at a lower
deposition temperature, it was surprising to find carbon particles
on the substrate surface, which are actually the reactive precursor
compounds falling down or sticking onto the deposited carbon
material. In contrast, the sources of particle contamination on a
substrate for a typical deposition of a material layer typically
come from degraded chamber wall, degraded chamber part components,
degraded ceramics or metal parts, o-rings, and/or other film
material before deposition.
As shown in FIG. 1, during the deposition of an amorphous carbon
film on a substrate, it was unexpected to observe carbon particle
contamination having a size of about 0.12 .mu.m or larger or about
0.16 .mu.m or larger at a deposition temperature of about
500.degree. C. or lower, such as at around 400.degree. C. or around
450.degree. C. In contrast, at a deposition temperature around
550.degree. C., no carbon particles are seen on the wafer.
Therefore, as the processing temperature is decreased from about
550.degree. C. to about 400.degree. C., the number of particles
resulting from the deposition increases. This is a problem when low
temperature deposition is required to be suitable for various
applications, such as aluminum applications.
The applications of using amorphous carbon as a hardmask are
widened by adjusting the deposition parameters and thus the film
property of the deposited amorphous carbon film. For example, it
can be used in front end processing, such as polysilicon gate or
oxide contact etch patterning. It can also be used for back end
DRAM processing where the underlying material is aluminum, using a
lower deposition temperature. However, particle contamination
increases as processing parameters change. In addition, decreasing
the deposition temperature decreases the absorbance of the film as
shown in FIG. 2. FIG. 2 demonstrates the correlation between the
deposition temperature and light absorption coefficient, k, of the
deposited amorphous carbon film at two different light wavelengths
of 248 nm (square dots) and 633 nm (diamond dots). In situations
requiring a more transparent film, desired lower extinction
coefficient (k) values for the absorbance of the film can be
achieved by depositing at lower temperatures. This can be
beneficial when performing wafer alignment in preparation for
lithograthy because alignment marks may not be detectable if the
carbon film is too absorbing. Also, in order to increase the
deposition rate of amorphous carbon and thus the throughput of
substrate processing, it is preferred to include a lower deposition
temperature, as shown in FIG. 3. Thus, it is desired to develop a
deposition process for amorphous carbon to reduce the particles
generated on the surface of the substrate at a low deposition
temperature.
SUMMARY OF THE INVENTION
Aspects of the invention generally provide a method for forming a
material layer, such as an amorphous carbon layer, deposited on a
dielectric material such as oxide, nitride, silicon carbide, carbon
doped oxide, etc., or a metal layer such as tungsten, aluminum or
poly-silicon with minimal defect formation and particle
contamination. In one aspect, a method for processing a substrate
in a chamber is provided. The method includes depositing a first
material inside the chamber for a first deposition time, then
positioning a substrate inside the chamber, and providing a gas
mixture by flowing one or more hydrocarbon compounds and an inert
gas to the deposition chamber. The method further includes applying
an electric field to the gas mixture and heating the gas mixture to
thermally decompose the one or more hydrocarbon compounds in the
gas mixture and generate a plasma, and depositing a second material
on the substrate for a second deposition time. Further, at least
one gas flow of the one or more hydrocarbon compounds is terminated
while still flowing the inert gas to the deposition chamber for a
first time period and any gas or plasma generated is pumped out of
the chamber for a second time period to reduce particle
contamination on the substrate.
In another aspect of the invention, a method for processing a
substrate includes positioning a substrate inside the chamber,
providing a gas mixture by flowing one or more hydrocarbon
compounds and an inert gas to the deposition chamber, applying an
electric field to the gas mixture and heating the gas mixture to
thermally decompose the one or more hydrocarbon compounds in the
gas mixture and generate a plasma, and depositing a material on the
substrate for a deposition time. The method further includes moving
the substrate to a different distance from a gas distribution
system of the chamber, terminating at least one gas flow of the one
or more hydrocarbon compounds while still flowing the inert gas to
the deposition chamber for a first time period, and pumping any gas
or plasma generated out of the chamber for a second time period to
reduce particle contamination on the substrate.
In still another aspect, a method for processing a substrate
includes depositing a material on the substrate for a deposition
time. The method further includes terminating at least one gas flow
of one or more hydrocarbon compounds while still flowing the inert
gas to the deposition chamber for a first time period and still
applying the electric field, and pumping any gas or plasma
generated out of the chamber for a second time period to reduce
particle contamination on the substrate.
In still another aspect, a method for processing a substrate
includes positioning a substrate inside the chamber, providing a
gas mixture by flowing one or more hydrocarbon compounds and an
inert gas to the deposition chamber, applying an electric field to
the gas mixture and heating the gas mixture to thermally decompose
the one or more hydrocarbon compounds in the gas mixture and
generate a plasma. The method further includes depositing a
material on the substrate for a deposition time and terminating the
electric field applied to the gas mixture. In addition, at least
one gas flow of the one or more hydrocarbon compounds is terminated
while still flowing the inert gas to the deposition chamber for a
first time period and still applying the electric field. Further,
any gas or plasma generated is pumped out of the chamber for a
second time period to reduce particle contamination on the
substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above features of the invention are
attained and can be understood in detail, a more particular
description of the invention, briefly summarized above, may be had
by reference to the embodiments thereof which are illustrated in
the appended drawings. It is to be noted, however, that the
appended drawings illustrate only typical embodiments of this
invention and are therefore not to be considered limiting of its
scope, for the invention may admit to other equally effective
embodiments.
FIG. 1 illustrates the effect of temperature on particle
contamination.
FIG. 2 illustrates the effect of temperature on extinction
coefficient of film absorbance.
FIG. 3 illustrates the effect of temperature on deposition
rate.
FIG. 4 is a perspective view of one embodiment of the vacuum
processing system of the present invention.
FIG. 5 is a cross sectional view of one embodiment of a processing
chamber of the present invention.
FIG. 6 is a process flow diagram illustrating a first method
incorporating one embodiment of the invention.
FIG. 7 is a process flow diagram illustrating a second method
incorporating one embodiment of the invention.
FIG. 8 is a process flow diagram illustrating a third method
incorporating one embodiment of the invention.
FIG. 9 is a process flow diagram illustrating a fourth method
incorporating one embodiment of the invention.
FIG. 10 illustrates the effect of seasoning on numbers of particles
generated.
FIG. 11 illustrates the effect of wide spacing lift on numbers of
particles generated.
FIG. 12 illustrates the effect of purge conditions on numbers of
particles generated.
FIG. 13 illustrates purge conditions.
FIG. 14 illustrates the effect of purge conditions and RF power on
numbers of particles generated.
FIG. 15 compares the effect of purge conditions in the presence of
RF power on numbers of particles generated.
For a further understanding of aspect of the invention, reference
should be made to the ensuing detailed description. The words and
phrases used herein should be given their ordinary and customary
meaning in the art by one skilled in the art unless otherwise
further defined.
DETAILED DESCRIPTION
Aspects of the invention generally provide a method for forming a
material layer and removing particle contamination from the
material layer, such as an amorphous carbon layer deposited on a
dielectric material such as oxide, nitride, silicon carbide, carbon
doped oxide, etc., or a metal layer such as tungsten, aluminum or
poly-silicon. For example, an amorphous carbon layer is formed by
thermally decomposing a gas mixture comprising a hydrocarbon
compound and an inert gas. The gas mixture is introduced into a
process chamber where plasma enhanced thermal decomposition of the
hydrocarbon compound, in close proximity to the surface of a
substrate, results in deposition of an amorphous carbon layer on
the substrate surface. The amorphous carbon layer is compatible
with integrated circuit fabrication processes. In one integrated
circuit fabrication process, the amorphous carbon layer is used as
a hardmask. The amorphous carbon layer is also suitable for use as
an anti-reflective coating (ARC) at DUV wavelengths. Additionally,
the pattern defined in the amorphous carbon hardmask can be
incorporated into the structure of an integrated circuit, such as
for example in a damascene structure.
In one embodiment, when an amorphous carbon layer is deposited at a
lower deposition temperature, the amorphous carbon layer is
deposited from a gas mixture having one or more hydrocarbon
compounds, wherein the flow of the one or more hydrocarbon
compounds into the processing chamber is terminated before the flow
of the other components of the gas mixture into the chamber. This
helps to reduce particle contamination without the need for
additional process steps or complicated adjustments on the chamber
hardware.
In another embodiment, a first material is deposited inside the
chamber before a second material is deposited on the substrate to
help reduce particle contamination. In still another embodiment,
the substrate is moved such that it is located at a different
distance from a gas distribution system of the chamber after the
amorphous carbon layer is deposited on the substrate. In still
another embodiment, after the amorphous carbon layer is deposited,
the flow of the one or more hydrocarbon compounds into the
processing chamber is terminated while the flow of the other
components of the gas mixture and the RF power are continued.
Generally, one or more processing conditions are varied during the
deposition of a material layer such that plasma-induced particle
contamination to the substrate is reduced. This embodiment will be
further described with respect to FIGS. 4 6.
FIG. 4 is a perspective view of a vacuum processing system that is
suitable for practicing embodiments of the invention and FIG. 5 is
a cross-sectional schematic view of a chemical vapor deposition
(CVD) chamber 106 that is suitable for practicing embodiments of
the invention. One example of such a chamber is a PRODUCER.RTM.
dual chambers or a DxZ.RTM. chamber, used in a P-5000 mainframe or
a CENTURA.RTM. platform, suitable for 200 mm, 300 mm, or larger
size substrates, all of which are available from Applied Materials,
Inc., of Santa Clara, Calif. In FIG. 4, the system 100 is a
self-contained system supported on a main frame structure 101 where
wafer cassettes are supported and wafers are loaded into and
unloaded from a loadlock chamber 112, a transfer chamber 104
housing a wafer handler, a series of tandem process chambers 106
mounted on the transfer chamber 104 and a back end 108 which houses
the support utilities needed for operation of the system 100, such
as a gas panel, power distribution panel and power generators. The
system can be adapted to accommodate various processes and
supporting chamber hardware such as CVD, PVD and etch. The
embodiment described below will be directed to a system employing a
CVD process, such as plasma enhanced CVD processes, to deposit a
material, such as an amorphous carbon material.
FIG. 5 shows a schematic cross-sectional view of the chamber 106
defining two processing regions 618, 620. Chamber body 602 includes
chamber sidewall 612, chamber interior wall 614 and chamber bottom
wall 616 which define the two processing regions 618, 620. The
bottom wall 616 in each processing region 618, 620 defines at least
two passages 622, 624 through which a stem 626 of a heater pedestal
628 and a rod 630 of a wafer lift pin assembly are disposed,
respectively.
The chamber 106 also includes a gas distribution system 608,
typically referred to as a "showerhead", for delivering gases into
the processing regions 618, 620 through a gas inlet passage 640
into a shower head assembly 642 comprised of an annular base plate
648 having a blocker plate 644 disposed intermediate a face plate
646. A plurality of vertical gas passages are also included in the
shower head assembly 642 for each reactant gas, carrier gas, and/or
cleaning gas to be delivered into the chamber through the gas
distribution system 608.
A heater pedestal 628 is movably disposed in each processing region
618, 620 by a stem 626 which is connected to a lift motor 603. The
stem 626 moves upwardly and downwardly in the chamber to move the
heater pedestal 628 to position a substrate (not shown) thereon or
remove a substrate there from for processing. Gas flow controllers
are typically used to control and regulate the flow rates of
different process gases into the process chamber 106 through gas
distribution system 608. Other flow control components may include
a liquid flow injection valve and liquid flow controller (not
shown) if liquid precursors are used. A substrate support is
heated, such as by a heater having one or more resistive elements,
and is mounted on the stem 626, so that the substrate support and
the substrate can be controllably moved by a lift motor 603 between
a lower loading/off-loading position and an upper processing
position adjacent to the gas distribution system 608.
The chamber sidewall 612 and the chamber interior wall 614 define
two cylindrical annular processing regions 618, 620. A
circumferential pumping channel 625 is formed in the chamber walls
for exhausting gases from the processing regions 618, 620 and
controlling the pressure within each region 618, 620. A chamber
liner or insert 627, preferably made of ceramic or the like, is
disposed in each processing region 618, 620 to define the lateral
boundary of each processing region and to protect the chamber
sidewalls 612 and the chamber interior wall 614 from the corrosive
processing environment and to maintain an electrically isolated
plasma environment. A plurality of exhaust ports 631, or
circumferential slots, are located about the periphery of the
processing regions 618, 620 and disposed through each liner 627 to
be in communication with the pumping channel 625 formed in the
chamber walls and to achieve a desired pumping rate and uniformity.
The number of ports and the height of the ports relative to the
face plate of the gas distribution system are controlled to provide
an optimal gas flow pattern over the wafer during processing.
A plasma is formed from one or more process gases or a gas mixture
by applying an electric field from a power supply and heating the
gas mixture, such as by the resistive heater element. The electric
field is generated from coupling, such as inductively coupling or
capacitively coupling, to the gas distribution system 608 with
radio-frequency (RF) or microwave energy. In some cases, the gas
distribution system 608 acts as an electrode. Film deposition takes
place when the substrate is exposed to the plasma and the reactive
gases provided therein. The substrate support and chamber walls are
typically grounded. The power supply can supply either a single or
mixed-frequency RF signal to the gas distribution system 608 to
enhance the decomposition of any gases introduced into the chamber
106. When a single frequency RF signal is used, e.g., between about
350 kHz and about 60 MHz, a power of between about 1 and about
2,000 W can be applied to the gas distribution system 608.
A system controller controls the functions of various components
such as the power supplies, lift motors, flow controllers for gas
injection, vacuum pump, and other associated chamber and/or
processing functions. The system controller executes system control
software stored in a memory, which in the preferred embodiment is a
hard disk drive, and can include analog and digital input/output
boards, interface boards, and stepper motor controller boards.
Optical and/or magnetic sensors are generally used to move and
determine the position of movable mechanical assemblies. A similar
system is disclosed in U.S. Pat. No. 5,855,681, entitled "Ultra
High Throughput Wafer Vacuum Processing System," issued to Maydan
et al., filed on Nov. 18, 1996, also in U.S. Pat. No. 6,152,070,
entitled "Tandem Process Chamber," issued to Fairbairn et al.,
filed on Nov. 18, 1996. Both are assigned to Applied Materials,
Inc., the assignee of the present invention. Another examples of
such a CVD process chamber is described in U.S. Pat. No. 5,000,113,
entitled "Thermal CVD/PECVD Reactor and Use for Thermal Chemical
Vapor Deposition of Silicon Dioxide and In-situ Multi-step
Planarized Process," issued to Wang et al., and in U.S. Pat. No.
6,355,560, entitled "Low Temperature Integrated Metallization
Process and Apparatus," issued to Mosely et al. and assigned to
Applied Materials, Inc. The aforementioned patents are hereby
incorporated by reference to the extent not inconsistent with the
disclosure herein. The above CVD system description is mainly for
illustrative purposes, and other plasma processing chambers may
also be employed for practicing embodiments of the invention.
FIG. 6 is a process flow diagram illustrating a first embodiment of
the invention. At step 501, a first material is deposited inside a
chamber for a first deposition time, such as about 1 second or
larger. Preferably, the first deposition time is between about 5
seconds to about 30 seconds, such as about 10 seconds. At step 502,
a substrate for depositing a second material thereon is positioned
on a substrate support inside the chamber. In one embodiment, the
first material may be the same material as the second material that
is deposited on the substrate. It was found that the deposition of
the first material inside the chamber before the second material is
deposited on the substrate reduces the number of particles
contaminating on the substrate surface, as compared to no
deposition of the first material, as described in detail also in
Examples.
At step 503, a gas mixture is introduced into the chamber. The gas
mixture may include various process gas precursors for depositing a
second material (e.g., an amorphous carbon material), various
carrier gases, and inert gases. In one embodiment, the gas mixture
includes one or more hydrocarbon compounds and an inert gas. At
step 504, RF power is initiated in the chamber in order to provide
plasma processing conditions in the chamber. The gas mixture is
reacted in the chamber in the presence of RF power to deposit the
second material on the substrate at step 505 for a second
deposition time, such as about 5 second or more. Preferably, the
second deposition time is between about 5 seconds or longer, such
as about 60 seconds. In one embodiment, the first deposition time
is shorter than the second deposition time.
At step 506, the flow of one or more process gas precursors is
terminated. For example, the flow of one or more hydrocarbon
compounds is terminated. It is contemplated that, in one
embodiment, by terminating the flow of the one or more hydrocarbon
compounds immediately after the second material is deposited on the
substrate, the source of the particle contamination, the one or
more hydrocarbon compounds, is reduced inside the chamber, thereby
reducing the chance for particles to fall down onto the substrate
surface.
At step 507, other gas flow in the gas mixture is maintained for a
first time period. For example, the flow of a carrier gas or an
inert gas is continued to help purge particles, such as carbon
particles, away from the substrate surface. The first time period
for maintaining the flow of the inert gas, such as a helium gas, is
about 1 second or larger. Preferably, the first time period for
inert gas purge is between about 1 second to about 1 minute, such
as between about 5 seconds to about 180 seconds, e.g., a first time
period of about 5 seconds to about 10 seconds.
At step 508, any particles, contamination, gas, such as
precursor-containing gas, carrier gas, inert gas, or plasma
remained inside the chamber, is pumped out of the chamber for a
second time period, before the remaining gas flow from the gas
mixture is terminated at step 509, for example, before the flow of
the inert gas is terminated. The second time period for pumping
contamination, gas, or plasma is about 1 second or larger.
Preferably, the second time period is between about 1 second to
about 3 minutes, such as between about 5 seconds to about 60
seconds, e.g., a second time period of about 10 seconds. In one
embodiment, the first time period is the same as the second time
period. In another embodiment, the first time period shorter than
the second time period. At step 510, the substrate is removed from
the chamber, for example, by opening a chamber slit valve.
Although FIG. 6 includes two steps, 501 and 506, in which a first
material is deposited inside the chamber before a second material
is deposited on the substrate, and one or more process gas flows is
terminated, in other embodiments, only one of steps 501 and 506 is
performed. For example, a carbon film may be deposited shortly
after in-situ oxygen plasma cleaning to reduce carbon particle
contamination in the later substrate deposition step regardless of
whether or not one or more process gas flow is terminated during
the process sequence. The deposition of this carbon film takes
place without the presence of the substrate for a short first
deposition time, such as about 1 second or longer, e.g., between
about 5 seconds to about 10 seconds. The carbon film is generally
deposited on chamber walls, face plate, etc. The substrate is not
placed in the chamber until after this first deposition time to
ensure that the substrate is under the same condition before and
after it goes into the chamber.
The mechanism by which carbon particle contamination increases at
lower deposition temperatures is not clear. It is hypothesized that
gas phase nucleation of reactive carbon and hydrogen containing
fragments undergoes an effect called thermophoresis at different
deposition temperatures. In general, particles move from a hotter
to a colder region in a temperature gradient. By heating a surface
sufficiently, a thermophoretic force is generated that is
sufficient to overpower gravitational, electrostatic, and
convectional forces.
When the heater near the substrate support is set at a higher
temperature, e.g., at 550.degree. C., the rest of the chamber walls
and plasma are much colder; so there is a very strong temperature
gradient in the gas/plasma inside the chamber to help keep the
particles away from the substrate surface, strong enough to keep
particles of a certain size from depositing on a hotter
surface.
When deposition takes place at a lower temperature, e.g., at
400.degree. C., the temperature gradient inside the chamber is no
longer big enough and contamination such as some of the carbon
particles may fall down on top of the substrate. It is believed
that, at 400.degree. C., the temperature gradient created between
the heated substrate and the gas/plasma phase is insufficient to
prevent the movement of particles created in the plasma phase onto
the substrate surface.
Other possible mechanisms that relate to the amount of particles
deposited are the quality of the first material deposited inside
the chamber before the substrate is positioned in the chamber. In
addition, contamination can also stick onto the substrate by
electrostatic force.
FIG. 7 is a flow diagram of a second embodiment of the invention
that may be performed using a processing chamber such as the
processing chamber shown in FIG. 4. In the embodiment shown in FIG.
7, the amorphous carbon layer is deposited, and any contamination,
gas, or plasma is pumped out of the chamber.
At step 701, a substrate is positioned on a substrate support in a
processing chamber. At step 702, a gas mixture, such as a mixture
of one or more hydrocarbon compounds and an inert gas, is
introduced into the chamber. At step 703, RF power is initiated in
the chamber in order to provide plasma processing conditions in the
chamber. At step 704, a material, such as an amorphous carbon
material, is deposited on the substrate for a deposition time of
between about 5 seconds or longer, such as about 60 seconds.
At step 705, the substrate is moved to a different distance from
the gas distribution system of the chamber. In one embodiment, the
substrate is moved to a different distance from the gas
distribution system than the substrate position at step 704 to
prevent particle contamination on the substrate. In another
embodiment, the substrate is moved by the lift motor 603 to a
position close to the exhaust port 631 in communication with the
pumping channel 625. In still another embodiment, the substrate is
moved by the lift motor 603 to a lower loading/off-loading
position.
At step 706, the flow of the one or more hydrocarbon compounds is
terminated, while the inert gas flow is continued at step 707 for a
first time period of 1 second or longer, such as between about 5
seconds to about 60 seconds, such as about 20 seconds. At step 708,
the gas exhaust pump is turned on for a second time period of 1
second or longer, such as between about 5 seconds to about 120
seconds, such as about 30 seconds, to pump any gas or plasma out of
the chamber. In one embodiment, the first time period is the same
as the second time period. In another embodiment, the second
embodiment is longer than the second embodiment. At step 709, flow
of the remaining component of the gas mixture is terminated. For
example, the inert gas is terminated, and the substrate is ready to
be removed from the chamber at step 710.
FIG. 8 is a flow diagram of a third embodiment of the invention. In
the embodiment shown in FIG. 8, the amorphous carbon layer is
deposited, wherein the flow of the one or more hydrocarbon
compounds into the processing chamber is terminated while both the
flow of the other components of the gas mixture into the chamber
and the RF power are continued.
At step 801, a substrate is positioned on a substrate support in a
processing chamber. At step 802, a gas mixture, such as a mixture
of one or more hydrocarbon compounds and an inert gas, is
introduced into the chamber and the RF power is initiated at step
803. At step 804, a material, such as an amorphous carbon material,
is deposited on the substrate for a deposition time of between
about 5 seconds or longer, such as about 60 seconds. At step 805,
the flow of the one or more hydrocarbon compounds is terminated,
while the inert gas flow and the RF power are continued at step 806
for a first time period of 1 second or longer. The flow of the
inert gas flow in the presence of the RF power can help to reduce
particle contamination on the substrate. At step 807, any gas,
plasma, and particles are pumped out of the chamber, pumping for a
second time period of about 1 second or longer. At step 808, the
remaining components of the gas mixture, the RF power, the inert
gas flow are terminated before the substrate is removed from the
chamber at step 809.
The combination of the steps of FIGS. 7 and 8 provides another
embodiment of the invention. A substrate is positioned on a
substrate support in a processing chamber, a gas mixture is
introduced into the processing chamber, RF power is initiated in
the processing chamber to provide plasma processing conditions in
the chamber, and the gas mixture having one or more hydrocarbon
compounds and an inert gas is reacted in the chamber in the
presence of RF power to deposit an amorphous layer on the substrate
for a deposition time. Then, the substrate is moved to a different
distance from the gas distribution system of the chamber and the
flow of the one or more hydrocarbon compounds into the chamber is
terminated, as shown in steps 701 706 of FIG. 7. In addition, the
inert gas flow and the RF power are continued for a first time
period of 1 second or longer, and any gas, plasma, and particles
are pumped out of the chamber before the substrate is removed from
the chamber, as shown in steps 806 809 of FIG. 8.
FIG. 9 is a flow diagram of another embodiment of the invention. In
the embodiment shown in FIG. 9, the amorphous carbon layer is
deposited, wherein the flow of the one or more hydrocarbon
compounds into the processing chamber and the RF power are
terminated while the flow of the other components of the gas
mixture into the chamber is remained.
At step 901, a substrate is positioned on a substrate support in a
processing chamber. At step 902, a gas mixture, such as a mixture
of one or more hydrocarbon compounds and an inert gas, is
introduced into the chamber and the RF power is initiated at step
903. At step 904, a material, such as an amorphous carbon material,
is deposited on the substrate for a deposition time. At step 905,
the flow of the one or more hydrocarbon compounds is terminated. At
step 906, the RF power is terminated, while the inert gas flow is
continued at step 907 for a first time period of 1 second or
longer. The flow of the inert gas flow can help to reduce particle
contamination on the substrate. At step 908, any gas, plasma, and
particles are pumped out of the chamber for a second time period of
1 second or longer. At step 909, the remaining components of the
gas mixture and the inert gas flow are terminated before the
substrate is removed from the chamber at step 910.
The combination of the steps of FIGS. 7 and 9 provides another
embodiment of the invention. A substrate is positioned on a
substrate support in a processing chamber, a gas mixture is
introduced into the processing chamber, RF power is initiated in
the processing chamber to provide plasma processing conditions in
the chamber, and the gas mixture having one or more hydrocarbon
compounds and an inert gas is reacted in the chamber in the
presence of RF power for a deposition time of 1 second or longer to
deposit an amorphous layer on the substrate. Then, the substrate is
moved to a different distance from the gas distribution system of
the chamber, as shown in steps 701 705 of FIG. 7. In addition, the
flow of the one or more hydrocarbon compounds into the chamber and
the RF power are terminated, while the inert gas flow is continued
for a first time period, and any gas, plasma, and particles are
pumped out of the chamber for a second time period before the
substrate is removed from the chamber, as shown in steps 905 907 of
FIG. 9. Other embodiments include combinations of the steps of FIG.
6 and any of FIGS. 7 9 to include deposition of a first material
inside the chamber before a second material is deposited n the
substrate surface.
In FIGS. 6 9, additional steps may be included. For example, the
chamber may be cleaned with a plasma by supplying one or more
cleaning gases and applying an electric field from an RF power
source or microwave power source. The cleaning gases may include,
but are not limited to, oxygen-containing gas (e.g., oxygen, carbon
dioxide), hydrogen-containing gas (e.g., hydrogen gas),
nitrogen-containing gas (e.g., ammonium, nitrous oxide), helium,
argon, among others. Examples of hydrogen-containing gas include,
but are not limited to, hydrogen gas (H.sub.2) and ammonium
(NH.sub.3), among others. In one embodiment, when the chamber is
cleaned by a plasma generated from a cleaning gas, the cleaning gas
may optionally be delivered with a carrier gas and supplied into
the chamber. Exemplary carrier gas includes inert gases, such as
helium and argon, among others. In another embodiment, an in-situ
oxygen plasma is generated to clean away any material inside the
chamber, such as material on the chamber walls, face plate,
everywhere, after previous substrate processing and substrate
removal.
While the methods of reducing particle contamination described
above each include varying one process variable during the
deposition of an amorphous carbon layer, such as depositing a
carbon film inside the chamber before the amorphous carbon layer is
deposited on the substrate, the distance between the substrate and
the gas distribution system, the timing of the termination of the
flow of the one or more hydrocarbon compounds into the chamber, the
timing of the termination of the flow of the inert gas into the
chamber, the timing of the termination of the flow of the RF power
into the chamber, further embodiments include varying more than one
of these variables, not necessarily in the same order as
illustrated in FIGS. 6 9.
In one example, both deposition of the carbon film inside the
chamber before the amorphous carbon layer is deposited on the
substrate and alteration of the distance between the substrate and
the gas distribution system are required. In another example,
deposition of the carbon film inside the chamber before the
amorphous carbon layer is deposited on the substrate is required
and timing of the termination of the RF power into the chamber is
altered. In still another example, deposition of the carbon film
inside the chamber before the amorphous carbon layer is deposited
on the substrate and alteration of the distance between the
substrate and the gas distribution system are required, and the
timing of the termination of the flow of the one or more
hydrocarbon compounds and the flow of the inert gas and termination
of the RF power into the chamber are all altered.
For example, a substrate is positioned on a substrate support in a
processing chamber, RF power is initiated in the chamber in order
to provide plasma processing conditions in the chamber, a gas
mixture having one or more hydrocarbon compounds and an inert gas
is reacted in the chamber in the presence of RF power to deposit an
amorphous carbon layer on the substrate, and the flow of the one or
more hydrocarbon compounds into the chamber is terminated, while
the flow of the inert gas is continued. Then the substrate is moved
to a different distance from the gas distribution system and the RF
power and the flow of the rest of the gas mixture into the chamber
are terminated. Thereafter, pumping of any gas or plasma is
initiated to pump any particle contamination out of the chamber
before the inert gas flow is terminated and the substrate is
removed out of the chamber.
In other embodiments, in addition to varying the distance between
the substrate and the gas distribution system and/or varying the
timing of the initiation or termination of the flow of the one or
more hydrocarbon compounds into the chamber, a method of depositing
an amorphous carbon layer on a substrate such that particle
contamination to the substrate is minimized includes deposition of
the carbon film inside the chamber before the amorphous carbon
layer is deposited on the substrate, and varying the timing of the
flow of the inert gas and the initiation and/or termination of the
RF power.
For example, a carbon film is deposited inside the chamber before a
substrate is positioned on a substrate support in a processing
chamber, RF power is initiated in the chamber in order to provide
plasma processing conditions in the chamber, a gas mixture having
one or more hydrocarbon compounds and an inert gas is reacted in
the chamber in the presence of RF power to deposit an amorphous
carbon layer on the substrate. After deposition of the amorphous
carbon layer on the substrate, the flow of the one or more
hydrocarbon compounds into the chamber is terminated, and then the
substrate is moved such that it is located at a different distance
from a gas distribution system of the chamber. Then, the flow of
the inert gas is continued while pumping of any gas or plasma is
initiated to pump any particle contamination out of the chamber.
Shortly after, particle contamination is pumped out, the inert gas
flow is terminated and the substrate is removed out of the
chamber.
Precursors and Processing Conditions for Deposition of an Amorphous
Carbon Layer
In any of the embodiments described herein, an amorphous carbon
layer is deposited from a gas mixture having one or more
hydrocarbon compounds and an inert gas. The amorphous carbon layer
may be used as hardmask. The hardmask may be used at different
levels within a device and for different metal applications. The
hardmask layer can have a dielectric layer or a metal layer as an
underlying layer.
A wide variety of gas mixtures may be used to deposit the amorphous
carbon layer, and non-limiting examples of such gas mixtures are
provided below. Generally, the gas mixture may include one or more
hydrocarbon compounds and an inert gas. Suitable organic
hydrocarbon compounds include aliphatic organic compounds, cyclic
organic compounds, or combinations thereof. Aliphatic organic
compounds have linear or branched structures comprising one or more
carbon atoms. Organic hydrocarbon compounds contain carbon atoms in
organic groups. Organic groups may include alkyl, alkenyl, alkynyl,
cyclohexenyl, and aryl groups in addition to functional derivatives
thereof.
For example, the hydrocarbon compound can have a formula
C.sub.xH.sub.y, where x has a range of between 1 and 8 and y has a
range of between 2 and 18, including, but not limited to, methane
(CH.sub.4), ethane (C.sub.2H.sub.6), ethene (C.sub.2H.sub.4),
propylene (C.sub.3H.sub.6), propyne (C.sub.3H.sub.4), propane
(C.sub.3H.sub.8), butane (C.sub.4H.sub.10), butylene
(C.sub.4H.sub.8), butadiene (C.sub.4H.sub.6), acetelyne
(C.sub.2H.sub.2), benzene (C.sub.6H.sub.6), toluene
(C.sub.7H.sub.8), and combinations thereof. Alternatively,
partially or completely fluorinated derivatives of the hydrocarbon
compounds, for example, C.sub.3F.sub.8 or C.sub.4F.sub.8, may be
used to deposit a fluorinated amorphous carbon layer, which may be
described as an amorphous fluorocarbon layer. A combination of
hydrocarbon compounds and fluorinated derivatives of hydrocarbon
compounds may be used to deposit the amorphous carbon layer or
amorphous fluorocarbon layer.
Similarly, a variety of gases such as hydrogen (H.sub.2), nitrogen
(N.sub.2), ammonia (NH.sub.3), neon, xenon, krypton, or
combinations thereof, among others, may be added to the gas mixture
to modify properties of the amorphous carbon material. Argon,
helium, and nitrogen are used to control the density and deposition
rate of the amorphous carbon layer. The addition of H.sub.2 and/or
NH.sub.3 can be used to control the hydrogen ratio of the amorphous
carbon layer to control layer properties, such as reflectivity.
A preferred amorphous carbon layer is deposited in one embodiment
by supplying propylene or propane to a plasma processing chamber at
a flow rate between about 200 standard cubic centimeters per minute
(sccm) and about 5000 sccm. An inert gas, such as helium, argon, or
combinations thereof, is also supplied to the chamber at a flow
rate between about 200 sccm and about 5000 sccm. The chamber
pressure is maintained between about 100 milliTorr and about 20
Torr.
The gas mixture is introduced to the processing chamber via a gas
distribution system spaced between about 180 mils and about 2000
mils from the substrate on which the amorphous carbon layer is
being deposited upon. Power from a single 13.56 MHz RF power source
is sup plied to the chamber 106 to form the plasma at a power
density between about 0.14 watts/cm.sup.2 and about 8.6
Watts/cm.sup.2, or a power level between about 100 watts and about
6000 watts for a 300 mm substrate. A power density between about
0.9 watts/cm.sup.2 and about 2.8 watts/cm.sup.2, or a power level
between about 600 watts and about 2000 watts for a 300 mm
substrate, is preferably supplied to the processing chamber to
generate the plasma. During deposition of the amorphous carbon
layer, the substrate is maintained at a temperature between about
-20.degree. C. and about 550.degree. C., and preferably is
maintained at a temperature between about 350.degree. C. and about
450.degree. C. The RF power is provided at a frequency between
about 0.01 MHz and 300 MHz. The RF power may be provided
continuously or in short duration cycles. RF power is coupled to
the deposition chamber to increase dissociation of the compounds.
The compounds may also be dissociated in a microwave chamber prior
to entering the deposition chamber. However, it should be noted
that the respective parameters may be modified to perform the
plasma processes in various chambers and for different substrate
sizes, such as 200 mm substrates, among others.
The above process parameters provide a typical deposition rate for
the amorphous carbon layer in the range of about 100 .ANG./min to
about 4500 .ANG./min and can be implemented on a 300 mm substrate
in a deposition chamber, such as the Producer SE system or the
DxZ.TM. processing chamber, commercially available from Applied
Materials, Inc. The applied RF power may be varied based upon the
substrate size and the equipment used, for example, the applied RF
power may be between about 0.9 watts/cm.sup.2 and about 2.8
watts/cm.sup.2. The amorphous carbon deposition values provided
herein are illustrative and should not be construed as limiting the
scope of the invention.
The amorphous carbon layer comprises carbon and hydrogen atoms,
which may be an adjustable carbon:hydrogen ratio that ranges from
about 10% hydrogen to about 60% hydrogen. Controlling the hydrogen
ratio of the amorphous carbon layer is desirable for tuning the
respective optical properties, etch selectivity and chemical
mechanical polishing resistance properties. Specifically, as the
hydrogen content decreases the optical properties of the
as-deposited layer such as for example, the index of refraction (n)
and the absorption coefficient (k) increase. Similarly, as the
hydrogen content decreases the etch resistance of the amorphous
carbon layer increases.
The light absorption coefficient, k, of the amorphous carbon layer
can be varied between about 0.1 to about 1.0 at wavelengths below
about 250 nm, such as between about 193 nm and about 250 nm, making
the amorphous carbon layer suitable for use as an anti-reflective
coating (ARC) at deep ultra-violet (DUV) wavelengths. The
absorption coefficient of the amorphous carbon layer can be varied
as a function of the deposition temperature. In particular, as the
temperature increases the absorption coefficient of the
as-deposited layer likewise increases. For example, when propylene
is the hydrocarbon compound, the k value for the as-deposited
amorphous carbon layers can be increased from about 0.2 to about
0.7 by increasing the deposition temperature from about 150.degree.
C. to about 480.degree. C.
The absorption coefficient of the amorphous carbon layer can also
be varied as a function of the additive used in the gas mixture. In
particular, the presence of hydrogen (H.sub.2), ammonia (NH.sub.3),
and nitrogen (N.sub.2), or combinations thereof, in the gas mixture
can increase the k value by about 10% to about 100%. The amorphous
carbon layer is further described in U.S. patent application Ser.
No. 09/590,322, filed on Jun. 8, 2000, entitled, "Method for
Depositing an Amorphous Carbon Layer", which is incorporated herein
to the extent not inconsistent with the claimed aspects and
description herein.
EXAMPLES
The following examples illustrate embodiments of the present
invention. The amorphous carbon layer was deposited using a
chemical vapor deposition chamber that is part of an integrated
processing platform. In particular, the films were deposited on a
300 mm PRODUCER SE.RTM. system, available from Applied Materials,
Inc. of Santa Clara, Calif.
Example 1
The chamber was pre-cleaned with an in-situ oxygen plasma by
supplying an oxygen gas and initiating a RF power. A carbon film
was then deposited inside the chamber at about 400.degree. C. for a
time period of 0, 5, 7, 10, 20, 30 seconds, or longer. This film is
also called seasoning film. A substrate is loaded onto the
substrate support of the chamber and an amorphous carbon layer was
deposited on the substrate from a gas mixture of propylene and
helium, having a chamber pressure of about 5.75 Torr and a
substrate temperature of about 400.degree. C. The substrate was
positioned 250 mils from the gas distribution manifold, and RF
power of 2.5 W/cm.sup.2 (1600 W) at a frequency of 13.56 MHz was
applied to the manifold. The gas mixture described above was
introduced into the chamber before the initiation of RF power.
After the amorphous carbon layer was deposited on the substrate,
the RF power and flow of the gas mixture were terminated. The
chamber slit valve was opened to allow the gas mixture to be pumped
out of the chamber. The numbers of the particles on the substrate
were measured to see the effect of the deposition of the carbon
film and the time period (thus, the thickness of the carbon film)
on particle contamination.
The results are shown in FIG. 10, which demonstrate that without
the seasoning film (deposition for a time period of 0 second),
shown as 1001, particles more than about 0.12 .mu.m were as many as
about 2100 or more. The number of particles generated can be
reduced to about 400, shown as 1004 in FIG. 10, in the case of
seasoning for about 10 seconds, and surprisingly, can be further
reduced by seasoning for a shorter period of time, such as for
about 7 seconds (shown as 1003 in FIG. 10), and preferably for
about 5 seconds (shown as 1002 in FIG. 10). It was concluded that,
under the deposition condition as described herein, the presence of
a seasoning carbon film before substrate deposition helped to
reduce particle contamination when deposited at a lower
temperature. Further, a certain thickness of the carbon film gave
less particles than other thicknesses, in this case, 5 seconds
seasoning was the optimum, which means basically quite a thin
coating, and no seasoning at all was worse. In general, the thinner
the seasoning film, the less particle contamination observed.
Example 2
Another example includes deposition of a carbon film at about
400.degree. C. for a time period of about 10 seconds. The substrate
was then introduced into the chamber and positioned 250 mils from
the gas distribution system. A gas mixture of propylene and helium
was introduced into the chamber before the initiation of RF power
and an amorphous carbon layer was deposited on a substrate at a
substrate temperature of about 400.degree. C. After the amorphous
carbon layer was deposited on the substrate, the RF power and flow
of the gas mixture were terminated. The substrate was then
positioned 1300 mils from the gas distribution system, while
maintaining the chamber pressure. The chamber slit valve was opened
to allow the gas mixture and/or plasma to be pumped out of the
chamber. The numbers of the particles on the substrate were
measured to see the effect of the position of the substrate from
the gas distribution system on particle contamination.
The results are shown in FIG. 10, which demonstrate that even in
the presence of a seasoning film, deposited for about 10 seconds,
particles more than about 0.12 .mu.m was further reduced when the
substrate was moved to a different distance from the gas
distribution system. For example, in FIG. 10, the numbers of
particles were measured from between 200 to 250, shown as 1101 for
substrate being about 250 mils away from the gas distribution
system, and were reduced to between 0 to 50, shown as 1102 for
substrate being about 1300 mils away from the gas distribution
system.
Example 3
Still another example includes pre-cleaning the chamber with an
in-situ oxygen plasma by supplying an oxygen gas and initiating a
RF power. No carbon film was deposited before an amorphous carbon
layer was deposited on a substrate from a gas mixture of propylene
and helium at a substrate temperature of about 400.degree. C. and
RF power of 1600 W) at a frequency of 13.56 MHz applied to the gas
distribution system. The flow of propylene was terminated while the
flow of helium is still on for about 20 seconds. The substrate was
positioned at about 250 mils from the gas distribution system. The
chamber slit valve was opened to allow the gas mixture to be pumped
out of the chamber. The numbers of the particles on the substrate
were measured to see the effect of purging particles out of the
chamber by the inert helium gas flow on particle contamination.
The results are shown in FIG. 12, which demonstrate that without
maintaining the inert helium gas, particles more than about 0.12
.mu.m was as many as about 2088 or more, shown as 1201. The number
of particles generated can be reduced to about 59, shown as 1202,
by maintaining the flow of the helium gas after the flow of the
propylene is terminated. The effect of this inert gas flow to
reduce carbon particle numbers is very significant. FIG. 12
demonstrates a total reduction of particle contamination for about
35 fold, comparably.
Example 4
As another example, the chamber was pre-cleaned with an in-situ
oxygen plasma by supplying an oxygen gas and initiating a RF power.
A carbon film was deposited before an amorphous carbon layer was
deposited on a substrate from a gas mixture of propylene and helium
at a substrate temperature of about 400.degree. C. and RF power of
1600 W at a frequency of 13.56 MHz applied to the gas distribution
system. The flow of propylene was terminated while the flow of
helium is still on for about 10 seconds at a flow rate of about
2500 sccm and a pressure of about 5 Torr. The substrate was moved
to about 1000 mils from the gas distribution system. The chamber
slit valve was then opened for about 5 seconds to allow the gas
mixture to be pumped out of the chamber. The numbers of the
particles on the substrate were measured to see the effect of
purging particles out of the chamber by the inert helium gas flow
on particle contamination.
The results are shown in FIG. 13, which demonstrate that without
maintaining the inert helium gas, particles more than about 0.12
.mu.m was as many as about 190 or more, shown as 1301. The number
of particles generated can be reduced to between about 21 and about
37, shown as 1302, by maintaining the flow of the helium gas after
the flow of the propylene is terminated. In this example, the
effect of this inert gas flow to reduce carbon particle numbers in
the presence of wider spacing between the substrate support and the
gas distribution system in FIG. 13 demonstrates a total reduction
of particle contamination for about 9 fold to about 5 fold.
Example 5
In another example, the chamber was pre-cleaned with an in-situ
oxygen plasma by supplying an oxygen gas and initiating a RF power.
A carbon film was deposited before an amorphous carbon layer was
deposited on a substrate from a gas mixture of propylene and helium
at a substrate temperature of about 400.degree. C. and RF power of
1600 W at a frequency of 13.56 MHz applied to the gas distribution
system. The flow of propylene was terminated while the flow of
helium at a flow rate of about 4500 sccm and RF power are
maintained for about 10 seconds. The substrate was moved to about
1000 mils from the gas distribution system. The chamber slit valve
was then opened for about 5 seconds to allow the gas mixture to be
pumped out of the chamber. The numbers of the particles on the
substrate were measured to see the effect of purging particles out
of the chamber by the inert helium gas flow in the presence or
absence of the RF power on particle contamination.
The results are shown in FIG. 14, which demonstrate that
maintaining the inert helium gas, particles more than about 0.12
.mu. were comparably the same. In FIG. 13, 1401 represents between
about 20 and 40 particles measured under the conditions of helium
purge for about 10 seconds without RF power and 1402 represents
between about 20 and 30 particles measured under the conditions of
helium purge for about 20 seconds in the absence of RF power. In
the presence of RF power, 1403 represents between about 20 and 45
particles measured under the conditions of helium purge for about
10 seconds.
Example 6
In still another example, we tested the effect of flow rate of the
inert gas, the pressure inside the chamber, and the distance
between the substrate support and the gas distribution system on
particle contamination. The chamber was pre-cleaned with an in-situ
oxygen plasma by supplying an oxygen gas and initiating a RF power.
A carbon film was deposited before an amorphous carbon layer was
deposited on a substrate from a gas mixture of propylene and helium
at a substrate temperature of about 400.degree. C. and RF power of
1600 W at a frequency of 13.56 MHz applied to the gas distribution
system. The flow of propylene was terminated while the flow of
helium at a flow rate of about 2500 sccm or about 4500 sccm is
maintained for about 10 seconds at a pressure of about 5.5 Torr or
about 0.5 1.0 Torr (TFO). The substrate was moved to about 900
mills or about 2000 mils from. the gas distribution system. The
chamber slit valve was then opened for about 5 seconds to allow the
gas mixture to be pumped out of the chamber. The numbers of the
particles on the substrate were measured.
The results are shown in FIG. 15, which demonstrate that higher
flow rate of helium gas, minimal pressure, and maximum spacing
between the substrate support and the gas distribution system
provide the best particle control. In FIG. 14, 1501 represents
between about 15 and 30 particles measured under the conditions of
helium purge for about 10 seconds at a flow rate of about 2500
sccm, a pressure of about 5.5 Torr, and a spacing of about 900 mils
from the gas distribution system, whereas, 1502 represents between
about 20 and 30 particles measured under the conditions of helium
purge for about 10 seconds at a flow rate of about 2500 sccm, a
pressure of about 5.5 Torr, and a spacing of about 1200 mils from
the gas distribution system. The best process conditions is shown
as 1503, representing between about 10 and 20 particles measured
under the conditions of helium purge for about 10 seconds at a flow
rate of about 4500 sccm, a pressure of about 0.5 1.0 Torr (TFO),
and a spacing of about 2000 mils from the gas distribution
system.
Example 7
In order to see the repeatability of the data and demonstrate the
robustness of the process conditions developed herein, about 1500
wafers were tested. For the first 1000 wafers, the helium gas flow
was maintained at the end of the deposition of an amorphous carbon
layer on the wafers. The last 500 wafers were prepared under the
conditions that the helium gas flow was maintained in the presence
of the RF power. The chamber was pre-cleaned with an in-situ oxygen
plasma by supplying an oxygen gas and initiating a RF power. A
carbon film was deposited for a deposition time of about 5 seconds
before an amorphous carbon layer was deposited on a substrate from
a gas mixture of propylene and helium at a substrate temperature of
about 400.degree. C. and RF power of 1600 W at a frequency of 13.56
MHz applied to the gas distribution system. The flow of propylene
was terminated while the flow of helium is continued. The wafers
were moved to a different distance from the gas distribution
system. The chamber slit valve was then opened to allow the gas
mixture to be pumped out of the chamber.
The numbers of the particles were measured after deposition of an
amorphous carbon layer on 1000 wafers under the conditions
described herein where the helium gas flow is continued and RF
power was turned off, and additional 500 wafers under the
conditions where both the helium gas flow and RF power are
continued to be turned on. The results show that particles more
then 0.12 .mu.m (square dots) were measured to be average of about
17 and particles more then 0.16 .mu.m (diamond dots) were measured
to be average of about 7.
In addition, the thickness and uniformity of the amorphous carbon
layer were measured after deposition under the conditions described
herein. The thickness of the deposited amorphous carbon layer is
about 2000 .ANG. and wafer-to-wafer average is about 2.4%. Also,
the refractive index of the amorphous carbon layer was measured
after deposition under the conditions described herein. The results
show that the refractive index at 248 nm of the deposited amorphous
carbon layer is about 1.64.+-.0.004 having a refractive index range
average of about 0.004. Further, the extinction coefficient factor
(k) of the amorphous carbon layer was measured after deposition of
an amorphous carbon material on 1000 wafers under the conditions
described herein where the helium gas flow is continued and RF
power was turned off, and additional 500 wafers under the
conditions where both the helium gas flow and RF power are
continued to be turned on. The results show that k at 248 nm value
of the amorphous carbon layer on the average is about 0.28.+-.0.01,
having a difference range of the k value for 1500 wafers to be
average at about 0.009.
While the foregoing is directed to preferred embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
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